#include<bits/stdc++.h>
using namespace std;
stack<int>stk;
int main(){
	cout << stk.empty() << endl;
	for(int i = 1 ; i <= 5 ; i++){
		stk.push(i);
	}
	stk.push(20);
	cout << stk.empty() << endl;
	cout << stk.size() << endl;
	cout << stk.top() << endl;
	stk.pop();
	cout << stk.top() << endl;
	while(!stk.empty()){
		stk.pop();
	}
	cout << stk.empty() << endl;
	return 0;
}
